This invention relates to a sticker emplacer for a lumber stacker. The invention is particularly related to use with a lumber stacker of the type in which several boards from a single layer, as for example from a conveyor, are grouped and formed into a layer, and successive layers are stacked. The stickers serve to space the successive layers apart from each other, and they comprise narrow boards running laterally across each layer of boards except the top layer.
Lumber is often seasoned. Seasoning is best done by providing suitable stacks of the lumber with each layer of the stack comprising several boards, with the layers kept apart from each other so that air can pass between them. Conventionally and quite satisfactorily when done right, the layers are spaced apart by shorter and smaller boards known as stickers. For example, each layer of lumber may be several feet across and many feet long, depending upon the length of the lumber, and the stickers run transversely across them, typically being about 1 .times. 2 inches and sufficiently long to run across the width of each layer. The stickers of each layer run parallel to each other and are typically spaced several feet apart from each other, at some desired distance.
The stacking and the placing of the stickers was formerly done by hand, and care was always taken to locate the stickers substantially in vertical alignment. Hand labor, however, is expensive and slow, and it has been desired to do the stacking mechanically both to reduce the ardor and the time taken to form the stacks manually and to reduce the number of laborers doing these menial hand jobs.
As a result, several machinery manufacturers offer lumber stackers. These differ from each other in various ways, but the one thing they have in common is that they accept lumber from a suitable conveyor usually moving transverse of the longitudinal axis of the boards, form a single layer of the boards, and then by various means stack the layers. The stackers are mechanical, and it is, of course, desirable to have the stickers put in place mechanically. They can be placed by hand, but to do so is time-consuming and awkward and results in a loss of much of the efficiency of the stacker.
However, the emplacing of stickers between successive layers of lumber has not been satisfactory in some stacking machines heretofore available. For example, one stacker which is otherwise an excellent machine emplaces the stickers from a series of stacks of sticker boards, usually formed manually by placing a number of stickers into a column between a pair of guides. Then this machine has laterally removed the bottom sticker of each stack at an appropriate time, moved it to one side, and dropped it on top of the boards of the main layer. This gave an approximate emplacement but not an exact one, and the inexactitude has had serious consequences.
The serious consequences are that some of the boards being seasoned may be warped if the stickers are not satisfactorily aligned vertically. Thus, when the stickers are approximately 1 .times. 2 inches, an emplacement of one sticker from its adjacent sticker by more than one-half of the width of the sticker has the result that the weight of the board layers on top presses down and forces the layer of boards on which this out-of-place sticker rests to flex downwardly on one side of the line of stickers, while the same layer is forced upwardly on the other side. This can cause very serious warping, and warping causes trouble later when the material is planed, as it usually is, or when it is used without planing. The cost of board warpage resulting from misplaced stickers is not known, but it must be a considerable amount. Naturally, this problem has caused severe dissatisfaction with stackers that misplace the stickers, as has been the case heretofore.
With the intention of remedying this difficulty, some of these prior-art sticker emplacers have utilized a hydraulic clamp to engage one end of the dropped sticker and hold it against the lumber stack before the other end is dropped. However, the hydraulic clamp does not act until the end it is to engage has dropped and probably bounced somewhat--usually too late to do any good, and the other end still drops down loosely.
The unevenness of the lumber itself--for the lumber is rarely sawn into exact thicknesses and therefore the layers are of uneven thickness--and the unevenness in the size of the stickers themselves causes dislocation and trouble, as well as the tendency of the sticker to bounce when it is dropped. Even if the stickers are initially made carefully and uniformly, as they themselves become seasoned and dried, they shrink, and therefore when they are reused, they are not all the same size, even if originally made so. It would be too expensive to plane them off at this time. Thus, the vibration, the bouncing, the unevenness, and several other factors combine to cause dislocation of stickers that are dropped, even though it might be thought that the dropping could be sufficiently accurate and smooth so that they could be held in place by a suitable hydraulic clamp. Such attempts have heretofore proved to be unsatisfactory. Some improvements may be obtained, but the amount is insufficient to make up for the difficulties that remain.
Therefore, an important object of the present invention is to provide a sticker emplacer that will more accurately locate the stickers so that they can be in sufficiently accurate alignment not to cause warpage of the boards.
Another object of the invention is to provide a mechanically operated sticker emplacer which requires a minimum of hand labor, usually confined to placing the sticker boards in between the guides that form the stacks of stickers.
Another object of the invention is to provide a sticker emplacer that is adaptable to various types of lumber stackers and can operate with these existing and known types of lumber stackers, which are satisfactory except for their sticker emplacement devices.
Another object of the invention is to provide a sticker emplacer which locates the stickers positively as part of the sequence of the lumber stacker itself, being synchronized with it so that the operations dovetail and thereby enable attainment of the maximum efficiency of operation in the lumber stacker itself.
Other objects and advantages of the invention will appear from the following descriptions.